Kitchen Ventilation System With Fan Having Positive Pressure-To-Output Characteristic Applied Thereto

ABSTRACT

The present invention relates to a kitchen ventilation system to which a fan having a positive pressure-to-output characteristic is applied. More particularly, the present invention relates to a system for maximizing efficiency of exhausting polluted air at minimum costs by applying a fan having a positive pressure-to-output characteristic to a hood, to improve a ventilation system which is installed vertically in an apartment house to discharge polluted air from kitchen hoods on respective floors to the top of an exhaust duct. The kitchen ventilation system of the present invention comprises an exhaust duct  100  provided at one side of an apartment house, and a hood  200  which is provided in the kitchen on each floor and includes a fan  210  having a positive pressure-to-output characteristic to collect surrounding air and discharge the collected air to the exhaust duct  100 . According to the present invention, noise can be reduced and economical efficiency and ventilation performance can also be improved by maximizing efficiency of exhausting polluted air at minimum costs.

TECHNICAL FIELD

The present invention relates to a kitchen ventilation system to which afan having a positive pressure-to-output characteristic is applied. Moreparticularly, the present invention relates to a system for maximizingefficiency of exhausting polluted air at minimum costs by applying a fanhaving a positive pressure-to-output characteristic to a hood, toimprove a ventilation system which is installed vertically in anapartment house to discharge polluted air from kitchen hoods inrespective floors to the top of an exhaust duct, thereby reducing noiseand improving economical efficiency and ventilation performance.

BACKGROUND ART

In general, a major source of polluting room air in an apartment houseis a variety of harmful materials such as heat, smell and oil vapor,which are produced when a person cooks in the kitchen. To discharge theharmful materials produced in the kitchen to the outside, a hood isinstalled in the kitchen, and an exhaust duct is also vertically formedon a side of the building to communicate with the kitchen hood.

FIG. 1 is a side sectional view of a conventional kitchen ventilationsystem.

As shown in FIG. 1, the conventional kitchen ventilation systemcomprises an exhaust duct 10 which is provided at one side of anapartment house and includes an exhaust fan 11 formed at an upper endthereof, a plurality of hoods 20 each of which is provided in thekitchen on each floor and includes a fan 21 to collect surrounding airand discharge the collected air to the exhaust duct 10, and a pluralityof pressure sensors 30 which are provided in the exhaust duct 10 atregular vertical intervals.

As shown in FIG. 1, the conventional kitchen ventilation system soconfigured allows the harmful and polluted materials, which are producedwhen a person cooks in the kitchen, to be collected in and discharged tothe outside through the exhaust duct 10 vertically formed on one side ofthe building, by means of the hood 20 mounted with the fan 21 which isinstalled over a countertop in the kitchen.

At this time, the fan 21 mounted to the hood 20 allows the pollutedmaterials in the kitchen to be collected and discharged to the exhaustduct 10, and the exhaust fan 11 allows the polluted materials in theexhaust duct 10 to be discharged to the outside of the building.

In general, in order to allow the fans 21 of the hoods 20 to smoothlydischarge the polluted materials in the kitchen to the outside in ahigh-rise building of 40 to 50 floors, the fans should exhibit output ofpower gradually increasing as installation positions are changed fromlower floors to higher floors.

However, when the hoods 20 with the same output of power as each otherare installed on the lower and higher floors, the output of power of thefan 21 in the hood 20 installed on the lower floors is unnecessarilylarge to discharge the polluted materials in the kitchen, whereas thatinstalled on the higher floors is insufficient to discharge the pollutedmaterials. Furthermore, there is a problem in that the fan 21 in thehood 20 installed in the kitchen on the higher floors cannot smoothlydischarge the polluted materials due to loss of static pressure as wellas the noise is too greatly increased.

That is, as load pressure applied to a discharge port of the fan 21 inthe hood 20 installed in the kitchen on the higher floors is increased,load applied to the fan 21 is also increased. Therefore, the amount ofair discharged is decreased, and thus, the amount of polluted materialsdischarged is also decreased.

To solve the above problem, the plurality of pressure sensors 30 areadditionally installed in the exhaust duct 10 at regular verticalintervals to independently control the output of power of the fans 21 inthe hoods 20 according to the pressure detected from the pressuresensors 30.

In case of the conventional kitchen ventilation system in which theplurality of pressure sensors measure air pressure in the exhaust ductat the respective levels to control the output of power of the fanaccording to the levels, however, there is a technical problem in thattotal manufacturing costs of the conventional kitchen ventilation systemare inevitably high due to the plurality of pressure sensors formeasuring the air pressure and a microprocessor for processing signalsfrom the pressure sensors to control the fans.

DISCLOSURE OF INVENTION

The present invention is conceived to solve the aforementioned problemin the prior art. An object of the present invention is to provide akitchen ventilation system to which a fan having a positivepressure-to-output characteristic is applied, wherein the fan having apositive pressure-to-output characteristic is employed in a kitchen hoodon each floor of an apartment house in which a common exhaust duct isused in both lower and higher floors of the apartment house such thatpolluted air in the kitchen can be effectively discharged withoutexpensive control devices such as a microprocessor or pressure sensorseven though different loads are applied to the lower and higher floors,whereby its noise can be reduced and its economical efficiency andventilation performance can also be improved by maximizing theefficiency of exhausting polluted air at minimum costs.

To achieve the object of the present invention, the kitchen ventilationsystem comprises an exhaust duct vertically provided at one side of anapartment house, and a hood for collecting surrounding air anddischarging the collected air to the exhaust duct, said hood beingprovided in a kitchen on each floor of the apartment hours and includinga fan having a positive pressure-to-output characteristic.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a side sectional view of a conventional kitchen ventilationsystem.

FIG. 2 is a side sectional view of a kitchen ventilation system to whicha fan having a positive pressure-to-output characteristic is appliedaccording to the present invention.

FIG. 3 is a circuit diagram of a fan driving circuit exhibiting apositive pressure-to-output characteristic for use in the kitchenventilation system to which the fan having a positive pressure-to-outputcharacteristic is applied according to an embodiment of the presentinvention.

FIG. 4 is a graph illustrating load curves and operating points of thefan driving circuit for use in a kitchen ventilation system to which afan having a positive pressure-to-output characteristic is appliedaccording to an embodiment of the present invention.

FIG. 5 is a circuit diagram of a fan driving circuit for use in akitchen ventilation system to which a fan having a positivepressure-to-output characteristic is applied according to anotherembodiment of the present invention.

FIG. 6 is a graph illustrating a level/output curve a fan having apositive pressure-to-output characteristic, which is installed at eachfloor and used in a kitchen ventilation system.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 2 is a side sectional view of a kitchen ventilation system to whicha fan having a positive pressure-to-output characteristic according tothe present invention is applied, and FIG. 3 is a circuit diagram of afan driving circuit for use in a kitchen ventilation system to which afan having a positive pressure-to-output characteristic is appliedaccording to an embodiment of the present invention.

FIG. 4 is a graph illustrating load curves and operating points of thefan driving circuit for use in a kitchen ventilation system to which afan having a positive pressure-to-output characteristic is appliedaccording to an embodiment of the present invention, FIG. 5 is a circuitdiagram of a fan driving circuit for use in a kitchen ventilation systemto which a fan having a positive pressure-to-output characteristic isapplied according to another embodiment of the present invention, andFIG. 6 is a graph illustrating a level/output curve a fan having apositive pressure-to-output characteristic, which is installed at eachfloor and used in a kitchen ventilation system.

As shown in FIG. 2, a kitchen ventilation system to which a fan having apositive pressure-to-output characteristic is applied comprises anexhaust duct 100 provided at one side of an apartment house, and a hood200 which is provided in the kitchen on each floor and includes a fan210 to collect surrounding air and discharge the collected air to theexhaust duct 100.

Hereinafter, the operation of the present invention will be explainedwith reference to FIGS. 2 to 6.

As shown in FIGS. 2 and 3, the kitchen ventilation system, to which thefan having a positive pressure-to-output characteristic is applied, ofthe present invention so configured allows the polluted materials, whichare produced when a person cooks in the kitchen, to be collected in anddischarged to the outside through the exhaust duct 100 vertically formedon one side of the building, by means of the hood 200 mounted with thefan 210 which is installed over a countertop in the kitchen. Inaddition, the fan 210 provided in the hood 200 allows the pollutedmaterials in the kitchen to be collected and discharged to the outsidethrough the exhaust duct 100.

A back draft damper is installed between the hood 200 and exhaust duct100 shown in FIG. 2 such that the polluted materials remaining in theexhaust duct 100 can be prevented from flowing back into the roomthrough the hood 200 when the fan 210 of the hood 200 is not in use.

At this time, in order to allow the fans 210 of the hood 200 to smoothlydischarge the polluted materials in the kitchen to the outside in ahigh-rise building of 40 to 50 floors, the fans 210 should exhibitoutput of power gradually increasing as their installation positions arechanged from lower floors to higher floors, as shown in FIG. 6.

To this end, it is preferable to provide the fan 210 having a positivepressure-to-output characteristic in each of the hoods 200 installed inthe kitchen on each floor of the building. In such a case, the fan 210having a positive pressure-to-output characteristic is installed in thehood 200 such that the hood installed in high-rise building can exhibitadequate output of power regardless of its installation level.Therefore, the polluted materials in the kitchen can be effectivelydischarged to the outside of the building, i.e. to the outside of theexhaust duct 100, without any additional exhaust fan.

The aforementioned fan 210 having a positive pressure-to-outputcharacteristic is preferably controlled by means of a fan drivingcircuit in which additional microprocessor and pressure sensors are notincluded. Preferably, the fan 210, which is provided in the hood 200 andhas a positive pressure-to-output characteristic, is driven by the fandriving circuit. As shown in FIG. 3, the fan driving circuit of thepresent invention comprises a 3-phase induction motor 310 for drivingthe fan 210, a power unit 320 for applying electric power to the 3-phaseinduction motor 310, a capacitor C2 330 which is connected with the3-phase induction motor 310 to produce a phase difference between twophases, and an impedance unit 340 which is connected in series with the3-phase induction motor 310 to produce a constant amount of airdischarged even though load applied to the fan 210 is changed.

Preferably, the impedance unit 340 includes capacitor C1 341 and aresistor Ri 342 connected in parallel with the capacitor C1 341.

As shown in FIG. 4, therefore, in cases where lower and higher voltages(respectively refer to curve A and curve B) are applied to the 3-phaseinduction motor 310 (refer to FIG. 3) according to the load applied tothe fan 210, operating points A′ and B′, which are operating on lowerand higher voltages, are shown along a load curve C, respectively.

That is, to create a positive pressure-to-output characteristic curve ofthe kitchen ventilation system mounted with the fan 210 serving as aload of the 3-phase induction motor 310, the impedance unit 340, whichincludes the capacitor C1 341 and the resistor R1 342 as a serial load,is added to a conventional driving circuit for the 3-phase inductionmotor 310 including a capacitor. Therefore, an alternating voltage withconstant amplitude is applied to the 3-phase induction motor 310 due tovoltage distribution of an alternating voltage with constant amplitudeand frequency between the 3-phase induction motor 310 including thecapacitor C2 330 and the impedance unit 340 serving as load in seriestherewith.

At this time, the fan driving circuit operates at equilibrium points forthe torque and rotating speed relationship due to the positivepressure-to-output characteristic curve shown in FIG. 4. In FIG. 4, acurve C is a load curve of the fan 210, a curve A is an outputcharacteristic curve of the 3-phase induction motor 310 when the lowervoltage is applied thereto, and a curve B is an output characteristiccurve of the motor when the higher voltage is applied thereto.

The operating principle will be discussed in detail with reference toFIGS. 3 and 4. If the load applied to the fan is increased while the3-phase induction motor 310 is rotating at a constant frequency at anoperating point A′, slip in the 3-phase induction motor 310 isincreased. Accordingly, equivalent impedance of the 3-phase inductionmotor 310 is reduced, and thus, the current is increased.

At this time, the rotating speed of the motor is rapidly increased dueto generated torque proportional to the square of current, and thus, theequivalent impedance of the 3-phase induction motor is again increased.Therefore, the voltage distributed to the constant serial load is alsoincreased (refer to curve B), and the motor is rotated at a newoperating point B′.

That is, under the load characteristic of the fan 210 having a positivepressure-to-output characteristic as shown in FIG. 4, an applied voltageis increased as the load is increased. Thus, the motor is in a stablestate at the operating point where the rotating speed of the motor ishigher.

On the contrary, if the load in the fan is decreased, the equivalentresistance is instantly increased and the current is simultaneouslydecreased. Thus, the rotating speed of the motor is rapidly reduced andthe equivalent impedance is also reduced, and the lower voltage isconsequently applied to the 3-phase induction motor 310 (refer to acurve A). Accordingly, the motor stably operates at a new operatingpoint A′.

That is, the load applied to the fan is continuously changed, and theoperating points can also be maintained between the maximum and minimumspeed-to-torque operating points that the 3-phase induction motor 310can operate.

As shown in FIG. 5, a fan driving circuit for use in a kitchenventilation system to which a fan having a positive pressure-to-outputcharacteristic is applied according to another embodiment of the presentinvention further comprises a resistor R2 350 connected in series withthe impedance unit 340 and a switch 360 connected in parallel with theresistor R2 350. Accordingly, the switch 360 can interrupt the currentflowing in the resistor R2 350.

That is, as shown in FIG. 5, if the switch 360 and resistor R2 350connected in parallel with each other are added to the fan drivingcircuit, resistance in the serial load is increased and the 3-phaseinduction motor 310 is kept at a lower rotating speed. At this time, ifthe switch 360 is turned on to cut off the current flowing in theresistor R2 350, the voltage distributed to the 3-phase induction motor310 is rapidly increased and thus the rotating speed of the fan 210 maybe rapidly increased.

INDUSTRIAL APPLICABILITY

According to the kitchen ventilation system of the present invention towhich a fan having a positive pressure-to-output characteristic isapplied, since the fan 210 controlled by the positive pressure-to-outputcharacteristic fan driving circuit is installed in the hood 200 providedin the kitchen of the high-rise building, the fan having a positivepressure-to-output characteristic can perform an active control of theoutput of power in accordance with a level where the hood 200 isinstalled. Therefore, there is an advantage in that polluted materialsin the kitchens on the respective floors can be easily dischargedthrough the exhaust duct 100 to the outside, because the fan 210 isrotating faster as the installation level is changed from lower floorsto higher floors.

Therefore, a fan having a positive pressure-to-output characteristic isemployed in the kitchen hood on each floor of an apartment house inwhich a common exhaust duct is used in both lower and higher floors ofthe apartment house such that polluted air in the kitchen can beeffectively discharged without expensive control devices such as amicroprocessor or pressure sensors even though different loads areapplied to the lower and higher floors, whereby noise can be reduced andeconomical efficiency and ventilation performance can also be improvedby maximizing the efficiency of exhausting polluted air at minimumcosts.

1. A kitchen ventilation system, comprising: an exhaust duct verticallyprovided at one side of an apartment house; and a hood for collectingsurrounding air and discharging the collected air to the exhaust duct,said hood being provided in a kitchen on each floor of the apartmenthouse and including a fan having a positive pressure-to-outputcharacteristic.
 2. The kitchen ventilation system as claimed in claim 1,wherein the fan, which is provided in the hood and has a positivepressure-to-output characteristic, is driven by a fan driving circuitwhich includes a 3-phase induction motor for driving the fan, a powerunit for applying electric power to the 3-phase induction motor, acapacitor C2 connected with the 3-phase induction motor for producing aphase difference between two phases, and an impedance unit connected inseries with the 3-phase induction motor for producing a constant amountof air discharged even though load applied to the fan is changed.
 3. Thekitchen ventilation system as claimed in claim 2, wherein the impedanceunit includes a capacitor C1, and a resistor R1 connected in parallelwith the capacitor C1.
 4. The kitchen ventilation system as claimed inclaim 2, wherein the fan driving circuit further comprises a resistor R2connected in series with the impedance unit and a switch installed inparallel with the resistor R2, thereby interrupting a current flowingalong the resistor R2.